(1) Field of the Invention
The invention relates to an image-detecting device, and more particularly to an energy-resolved X-ray image detector.
(2) Description of the Prior Art
X-ray imaging is usually seen in medical imaging, airport security inspection, industrial non-destructive testing and so on. Conventionally, an X-ray detecting device is used to detect an object able to reflect different X-rays intensities. However, in the X-ray detecting, only information of geometrical structuring of the object to be tested can be revealed, but material information of the object to be tested is yet to be realized. In the art, an apparatus able to discriminate energies of the X-ray beams has been developed recently. By this apparatus, the material information of the object to be tested can be understood by realizing different absorption characteristics of individual materials upon some X-ray beams with specific energies.
Currently, in the art of discriminating energies of X-ray beams, photon counting and stratified crystal techniques are mainly applied. In the photon counting technique, each X-ray beam is transformed into a corresponding electrical pulse signal by a detector, in which the magnitude of the electrical pulse signal is correlated to the energy of the X-ray beam. A comparator assigned with a threshold value is further applied at an electronic end to discriminate the magnitude of the electrical pulse signal. Though the threshold value can be relevantly adjusted to reach a required energy section, yet some more electric circuit components shall be added. However, such an addition of the electronic circuit components would increase structural complexity and manufacturing difficulty of the resulted circuit, and the cost as well. On the other hand, the stratified crystal technique adopts a multilayer scintillation crystal structure, which is obtained by laminating a plurality of scintillation crystals with different depths. By the dependency between the X-ray energy and the work depth of scintillation crystal, the X-ray beam with a weaker energy would react with the scintillation crystals in the superficial layers, while that with a stronger energy reacts with the scintillation crystals in the deeper layers. Positively, by utilizing the aforesaid physical properties to design crystal layers with individual thicknesses according to specific energy sections, lots of shortcomings in the conventional imaging techniques can be overcome. However, since more optoelectronic components shall be included, thus manufacturing thereof would be much more complicated, and the corresponding production cost would be higher.